Streetwise

Of Dangerous Books and Markets

Investors may misread between the lines. Chain retailers try window-dressing.

ONE OF THE SUMMER'S TWO SURPRISE NONFICTION BESTSELLERS is The Dangerous Book for Boys. The other, The Black Swan, might as well be called The Book for Dangerous Boys, so popular has it become among the same hedge-fund traders and sell-siders the author blames for raising the odds of a catastrophic financial surprise.

The former book is a nostalgic guide to traditional boyhood games and hobbies, meant to teach Wii-addicted, over-scheduled kids about supposedly simpler pleasures. The latter, a treatise on the way dramatic...